About

Luisa Hiller is an Associate Professor at Carnegie Mellon University in the Department of Biological Sciences and holds the Eberly Family Career Development Professorship. Her research focuses on microbial pathogenesis, utilizing a combination of comparative genomics, bioinformatics, and phylogenetics to develop hypotheses about gene function and test these hypotheses in in vivo and in vitro models. Her work aims to identify genomic patterns and correlate these with microbial molecular behaviors and host responses. Her comparative genomic studies have contributed to understanding pneumococcal strain diversity and the evolution of strains during naturally occurring chronic infections. Additionally, her studies on pandemic drug-resistant pneumococcal lineages reveal how gene transfer influences strain differentiation and virulence.

Research topics

• Biology
• Chemistry
• Biochemistry
• Cell biology
• Immunology
• Microbiology
• Biophysics

Selected publications

• Multi‐omics Analysis of <i>S. Pneumoniae</i> Extracellular Vesicles

  The FASEB Journal · 2022

  • Chemistry
  • Biochemistry
  • Biology

  Extracellular vesicles (EVs) are cell‐derived nanoparticles that can serve as carriers of DNA, RNA, and protein. For the pathogen S. pneumoniae, which causes diseases such as pneumonia and meningitis, EVs can be used to transport these macromolecules to recipient cells, facilitating communication and signaling between cells. However, the overall composition of these S. pneumoniae EVs is still unknown and how the macromolecules packaged within these EVs contribute to the pathogenicity of S. pneumoniae remains a hot research topic. In this work, we have developed a novel multi‐omic workflow that isolates DNA, RNA and protein from a single S. pneumoniae EV starting sample, enabling analysis of these macromolecules without the need for multiple sample preparation steps and allowing us to gain insights into the composition and functionality of S. pneumoniae EVs. EVs from a S. pneumoniae culture were isolated and the proteins in the EV homogenate were labeled with the bifunctional ProMTag. One end of the ProMTag forms a reversible, covalent bond with proteins. ProMTag’s other functional group is methyltetrazine, which forms an irreversible bond with trans‐Cyclooctene (TCO), allowing capture of EV proteins on TCO‐agarose beads. Organic solvent was then added to precipitate the nucleic acids in the EV homogenate. Nucleic acids were released by a series of washes and subsequently separated into DNA and RNA fractions by RNase or DNase treatment, respectively. Proteins were then released from the TCO‐agarose beads by reversing the ProMTag‐protein linkage, yielding proteins in their original, unmodified state ready for analysis. DNA and RNA were sequenced, and proteins were identified using mass spectrometry. Using this workflow, we were able to describe the composition of multiple macromolecules within S. pneumoniae EVs and gain insights into how these macromolecules might facilitate communication and infection within the S. pneumoniae population.

  DOI

• Membrane Protein Comparison Between Cell Membranes and ExtracellularVvesicle Membranes of <i>S. pneumoniae</i> Provide Insights into Extracellular Vesicle Formation and Shedding

  The FASEB Journal · 2022 · 1 citations

  • Chemistry
  • Biochemistry
  • Cell biology

  Extracellular vesicles (EVs) are complex, cell‐derived nanoparticles generated by all cell types. EVs are composed of lipid bilayer membranes and their associated membrane proteins, nucleic acids, and luminal proteins. The mechanism by which Gram‐positive bacteria shed EVs is still unknown. EVs from the Gram‐positive human pathogen S. pneumoniae , which is a major cause of otitis medi and pneumonia, are of particular interest because of how they EVs modulate the host immune response. To uncover possible mechanisms for EV production and shedding in S. pneumoniae, we have performed a comparative proteomics analysis of EV membrane proteins versus whole‐cell membrane proteins. Membrane proteins were enriched from intact S. pneumoniae cells or their EVs using a ProMTag labeling and capture workflow. ProMTag is a bifunctional protein tag where one moiety of the tag is able to form a reversible, covalent link to primary amines on proteins. The other moiety is methyltetrazine, which can form an irreversible, covalent bond with trans‐Cyclooctene (TCO) on the surface of beads to capture ProMTagged proteins for cleanup and elution. Using this workflow plasma membrane proteins can be tagged, captured, washed to remove non‐plasma membrane proteins, and then eluted in their original, unmodified state. In this study, intact cells and EVs from S. pneumoniae cultures were separated and the extracellular domains of membrane proteins in these two fractions were labeled with ProMTag. The membrane proteins were then enriched, washed, and eluted using the ProMTag workflow. These membrane protein populations were then TMT labeled and analyzed using mass spectrometry. Comparative analysis revealed membrane proteins that are concentrated or absent in EV membranes relative to bulk plasma membrane from whole cells, indicating a selective process for EV formation in S. pneumoniae. With this information, we present a new model for EV formation and shedding in S. pneumoniae.

  DOI

• Bacterial Extracellular Vesicle Mediated Host-Pathogen Interactions in Pneumococcal Infections

  The Journal of Immunology · 2020 · 1 citations

  Senior authorCorresponding
  • Microbiology
  • Biology
  • Immunology

  Abstract Extracellular vesicles (EVs) represent a highly sophisticated cell-to-cell mailing system across all biological kingdoms. EVs have long been characterized from many Gram-negative species and, recently from Gram-positive bacteria, including the major respiratory pathogen Streptococcus pneumoniae (pneumococcus). Our studies reveal that pneumococcal-derived vesicles can be internalized by macrophages, T cells, and epithelial cells. In vitro, EVs induce cytokine signaling in macrophages, including dose-dependent NF-kB signaling in murine RAW 264.7 and human primary macrophages. When administered systemically into a mouse, pneumococcal EVs result in splenomegaly and induced a sepsis-like cytokine storm. When immobilized in a hydrogel implant for local administration into a mouse, pneumococcal EVs recruited lymphocytes and macrophages. Moreover, pneumococcal lipoproteins are major contributors to NF-kB signaling and inflammatory responses, as these phenotypes were substantially reduced with EVs from a lipoprotein deficient strain (Δlgt) as compared to EVs from the wildtype strain. Taken together, in vivo studies suggest that pneumococcal vesicles alone are sufficient to induce inflammatory responses and tissue damage in mammalian hosts. Overall, our data suggest that pneumococcal EVs display potent immunomodulatory effects on host immune cells highlighting their pivotal role during the infectious process, either by manipulating host responses or by triggering host-defense systems. Thus, pneumococcal EVs are virulence determinants and may be effective tools for vaccine development.

  DOI

Frequent coauthors

• Bhanu P. Jena

  Wayne State University

  4 shared

• Scott G. Filler

  University of California, Los Angeles

  4 shared

• Adam Lacy‐Hulbert

  Benaroya Research Institute

  3 shared

• Rory Eutsey

  Carnegie Mellon University

  3 shared

• Stephanie Biedka

  Immediate Post Concussion Assessment and Cognitive Testing (United States)

  3 shared

• Aaron P. Mitchell

  University of Georgia

  3 shared

• Caroline Stefani

  Virginia Mason Medical Center

  3 shared

• Zhangyu Cheng

  Wenzhou Medical University

  2 shared

Labs

• Hiller LabPI

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